This is going to be an SPS-dominated build, and so adequate flow in the tank is a big concern. We are going to use both of the bulkheads in each stock overflow as drains. One will be a herbie (full-siphon) drain, and the other will be the emergency durso. We'll also be modding the weirs to lower, widen, and cut those narrow teeth out.
Since we're using all four B/H in the overflows as drains, we'll be needing a way to get the return from the sump back into the tank. For this, we are looking at two options; drilling another 1" BH in the right overflow and bringing the return up through there, or bringing it up the back of the tank into a 2' spraybar.
I have an initial design for the closed loop, but would appreciate your feedback on this. The plan is to use a Reeflo Dart to power the CL. I think a single 2" intake, and four 1" outlets should do the trick. We intend to plumb a 1.5" line from the Dart to a manifold with four 1" spa flex lines to each CL outlet.
Here's the drawing:
What do you think?